A general problem in designing a hearing aid is to deliver enough acoustical gain for the user in a broad frequency range (usually from 100 Hz to 10.000 Hz) depending on the hearing loss. This is usually achieved by either placing a speaker in an earpiece into the ear canal or by placing a loudspeaker behind the ear and lead the sound through a tube into the ear canal.
To achieve great output in the lower frequencies, the earpiece needs to seal well to the ear canal, and the venting in the earpiece needs to be small. This usually results in physical comfort problems for the user as well as the occlusion effect, making the users own voice uncomfortable. Additionally, users also dislike having something visible going into the ear canal.
An alternative way of delivering sound to the user's ear is through bone conduction. This is used in bone-anchored hearing aids for users with conductive hearing losses. In such case, the sound output is delivered as vibration to the skull. The vibrations travel through the skull bone and into the cochlear where the user can hear it as sound.
In the bone anchored solutions, the user gets a connector operated into the skull bone behind the ear, which the bone anchored hearing aid physically connects to.
For more mild hearing conductive hearing losses, the bone conducting hearing aid can also connect to the surface of the skin, either by using a head band or adhesive tape that hold the hearing aid towards the skin.
The bone-conducting hearing aid can also be built into hearing glasses, where the bone conducting transducer is placed behind the ear on the skin against the skull bone.
All of these bone conducting hearing aid related solutions usually require some force against the skin in order to deliver enough vibration to the user. This force can be uncomfortable for the user. These bone conducting hearing aid related solutions are generally acceptable for users with primarily conductive hearing loss, but usually not efficient enough for users with sensor-neural hearing loss (age related hearing loss).
The bone conducting hearing aids solves the problems with respect to comfort in the ear canal and visibility of something going into the ear canal. A problem is usually to get enough sound output through the skin on the skull bone. Further, at high output levels, the vibrations cause tingling discomfort on the skin, where the user can feel the vibrations.
Besides, hearing glasses is a smart way of combining hearing aids with glasses and opens up for a more discreet solution for users needing both.
There are two types of hearing glasses, namely, either having bone conducting (BC) transducers or air conducting (AC) transducers (or a combination of BC and AC).
The BC versions are a smart way of making a discreet delivery of the sound for the users through vibrations through the skin and skull into the user's cochlea. However, BC versions are limited by the low maximum force output (MFO), especially through the skin in the higher frequencies.
The AC versions do not have the same problems with maximum power output (MPO). The AC versions are usually constructed by having a speaker unit attached with a wire to the temple of the glasses and the other end of the wire to the speaker placed in the ear canal, similar to a receiver-in-the-ear (RITE) style hearing aid. There are also known AC versions with a speaker build into the temple of the glasses and then having a tube that leads the sound into an earpiece in the ear canal, similar to a behind-the-ear (BTE) style hearing aid. Both AC versions, with either a wire or a tube, make the hearing glasses less discreet and reduce the usability of the glasses. Namely, the earpiece is to be replaced every time the glasses are taken on and off.
Therefore, there is a need to provide a solution that addresses at least some of the above-mentioned problems. The present disclosure provides at least an alternative to the prior art.